A typical cellular wireless communication system employs a repeater to improve service quality at a cell edge. Features and functions of such repeater are defined in standard IEEE 802.16j. Such repeater has been frequently utilized in a network in order to improve the performance of a wireless communication system. In addition, the typical cellular wireless communication system employs orthogonal frequency division multiplexing (OFDM) to reduce complexity in a frequency selective channel at a receiving end.
Standards of a portable internet system and a wireless local area network (LAN), such as IEEE 802.16e and 802.16n, select OFDM as standard technology for a physical layer. Accordingly, a wireless communication system may be implemented based on OFDM technology. Therefore, it is worth attempting to increase the performance of the repeater network using the OFDM system and perform the repeater communication.
In a unidirectional repeater protocol, terminals may transmit and receive data through a repeater in four phases. When a unidirectional relay network is configured of a first terminal, a second terminal, and a repeater, data may be transmitted and received through four phases as follows. The first terminal transmits data to the repeater at the first phase and the repeater transmits the received data to the second terminal at the second phase. The second terminal transmits data to the repeater at the third phase. The repeater transmits the received data to the first terminal at the fourth phase.
In order to increase a transmission rating of a typical unidirectional relay network, a two-way repeater protocol has been introduced. When a two-way relay network is configured of a first terminal, a second terminal, and a repeater, data may be transmitted and received in two phases. For example, at the first phase, the first and second terminals simultaneously transmit data to the repeater. At the second phase, the repeater transmits the received data to the first terminal and the second terminal. The first and second terminals may decode data transmitted from other terminal by removing a self-interference signal from the received data. As described, the two-way repeater protocol may increase the synthesized transmission rating about twice much as compared to the unidirectional repeater protocol.
A typical power control method, however, has drawbacks such as power restrictions on terminals and a repeater as well as requiring a complex implementation algorithm.
When the synchronized power of terminals and a repeater is restricted in a two-way relay network, there is a need for developing a power control algorithm for increasing a synthesized transmission rating and a minimum transmission rating of an overall system.
Furthermore, there is a need for developing a power control algorithm having low complexity while considering restriction on the synthesized power of a terminal and a repeater.